NAME

Catalyst::Manual::Tutorial::Authentication - Catalyst Tutorial - Part 4: Authentication

OVERVIEW

This is Part 4 of 9 for the Catalyst tutorial.

DESCRIPTION

Now that we finally have a simple yet functional application, we can focus on providing authentication (with authorization coming next in Part 5).

This part of the tutorial is divided into two main sections: 1) basic, cleartext authentication and 2) hash-based authentication.

You can checkout the source code for this example from the catalyst subversion repository as per the instructions in Catalyst::Manual::Tutorial::Intro

BASIC AUTHENTICATION

This section explores how to add authentication logic to a Catalyst application.

Add Users and Roles to the Database

First, we add both user and role information to the database (we will add the role information here although it will not be used until the authorization section, Part 5). Create a new SQL script file by opening myapp02.sql in your editor and insert:

--
-- Add users and roles tables, along with a many-to-many join table
--
CREATE TABLE users (
        id            INTEGER PRIMARY KEY,
        username      TEXT,
        password      TEXT,
        email_address TEXT,
        first_name    TEXT,
        last_name     TEXT,
        active        INTEGER
);
CREATE TABLE roles (
        id   INTEGER PRIMARY KEY,
        role TEXT
);
CREATE TABLE user_roles (
        user_id INTEGER,
        role_id INTEGER,
        PRIMARY KEY (user_id, role_id)
);
--
-- Load up some initial test data
--
INSERT INTO users VALUES (1, 'test01', 'mypass', 't01@na.com', 'Joe',  'Blow', 1);
INSERT INTO users VALUES (2, 'test02', 'mypass', 't02@na.com', 'Jane', 'Doe',  1);
INSERT INTO users VALUES (3, 'test03', 'mypass', 't03@na.com', 'No',   'Go',   0);
INSERT INTO roles VALUES (1, 'user');
INSERT INTO roles VALUES (2, 'admin');
INSERT INTO user_roles VALUES (1, 1);
INSERT INTO user_roles VALUES (1, 2);
INSERT INTO user_roles VALUES (2, 1);
INSERT INTO user_roles VALUES (3, 1);

Then load this into the myapp.db database with the following command:

$ sqlite3 myapp.db < myapp02.sql

Add User and Role Information to DBIC Schema

This step adds DBIC-based classes for the user-related database tables (the role information will not be used until Part 5):

Edit lib/MyAppDB.pm and update the contents to match (only the MyAppDB => [qw/Book BookAuthor Author User UserRole Role/] line has changed):

package MyAppDB;

=head1 NAME 

MyAppDB -- DBIC Schema Class

=cut

# Our schema needs to inherit from 'DBIx::Class::Schema'
use base qw/DBIx::Class::Schema/;

# Need to load the DB Model classes here.
# You can use this syntax if you want:
#    __PACKAGE__->load_classes(qw/Book BookAuthor Author User UserRole Role/);
# Also, if you simply want to load all of the classes in a directory
# of the same name as your schema class (as we do here) you can use:
#    __PACKAGE__->load_classes(qw//);
# But the variation below is more flexible in that it can be used to 
# load from multiple namespaces.
__PACKAGE__->load_classes({
    MyAppDB => [qw/Book BookAuthor Author User UserRole Role/]
});

1;

Create New "Result Source Objects"

Create the following three files with the content shown below.

lib/MyAppDB/User.pm:

package MyAppDB::User;

use base qw/DBIx::Class/;

# Load required DBIC stuff
__PACKAGE__->load_components(qw/PK::Auto Core/);
# Set the table name
__PACKAGE__->table('users');
# Set columns in table
__PACKAGE__->add_columns(qw/id username password email_address first_name last_name/);
# Set the primary key for the table
__PACKAGE__->set_primary_key('id');

#
# Set relationships:
#

# has_many():
#   args:
#     1) Name of relationship, DBIC will create accessor with this name
#     2) Name of the model class referenced by this relationship
#     3) Column name in *foreign* table
__PACKAGE__->has_many(map_user_role => 'MyAppDB::UserRole', 'user_id');


=head1 NAME

MyAppDB::User - A model object representing a person with access to the system.

=head1 DESCRIPTION

This is an object that represents a row in the 'users' table of your application
database.  It uses DBIx::Class (aka, DBIC) to do ORM.

For Catalyst, this is designed to be used through MyApp::Model::MyAppDB.
Offline utilities may wish to use this class directly.

=cut

1;

lib/MyAppDB/Role.pm:

package MyAppDB::Role;

use base qw/DBIx::Class/;

# Load required DBIC stuff
__PACKAGE__->load_components(qw/PK::Auto Core/);
# Set the table name
__PACKAGE__->table('roles');
# Set columns in table
__PACKAGE__->add_columns(qw/id role/);
# Set the primary key for the table
__PACKAGE__->set_primary_key('id');

#
# Set relationships:
#

# has_many():
#   args:
#     1) Name of relationship, DBIC will create accessor with this name
#     2) Name of the model class referenced by this relationship
#     3) Column name in *foreign* table
__PACKAGE__->has_many(map_user_role => 'MyAppDB::UserRole', 'role_id');


=head1 NAME

MyAppDB::Role - A model object representing a class of access permissions to 
the system.

=head1 DESCRIPTION

This is an object that represents a row in the 'roles' table of your 
application database.  It uses DBIx::Class (aka, DBIC) to do ORM.

For Catalyst, this is designed to be used through MyApp::Model::MyAppDB.
"Offline" utilities may wish to use this class directly.

=cut

1;

lib/MyAppDB/UserRole.pm:

package MyAppDB::UserRole;

use base qw/DBIx::Class/;

# Load required DBIC stuff
__PACKAGE__->load_components(qw/PK::Auto Core/);
# Set the table name
__PACKAGE__->table('user_roles');
# Set columns in table
__PACKAGE__->add_columns(qw/user_id role_id/);
# Set the primary key for the table
__PACKAGE__->set_primary_key(qw/user_id role_id/);

#
# Set relationships:
#

# belongs_to():
#   args:
#     1) Name of relationship, DBIC will create accessor with this name
#     2) Name of the model class referenced by this relationship
#     3) Column name in *this* table
__PACKAGE__->belongs_to(user => 'MyAppDB::User', 'user_id');

# belongs_to():
#   args:
#     1) Name of relationship, DBIC will create accessor with this name
#     2) Name of the model class referenced by this relationship
#     3) Column name in *this* table
__PACKAGE__->belongs_to(role => 'MyAppDB::Role', 'role_id');


=head1 NAME

MyAppDB::UserRole - A model object representing the JOIN between Users and Roles.

=head1 DESCRIPTION

This is an object that represents a row in the 'user_roles' table of your application
database.  It uses DBIx::Class (aka, DBIC) to do ORM.

You probably won't need to use this class directly -- it will be automatically
used by DBIC where joins are needed.

For Catalyst, this is designed to be used through MyApp::Model::MyAppDB.
Offline utilities may wish to use this class directly.

=cut

1;

The code for these three result source classes is obviously very familiar to the Book, Author, and BookAuthor classes created in Part 2.

Sanity-Check Reload of Development Server

We aren't ready to try out the authentication just yet; we only want to do a quick check to be sure our model loads correctly. Press Ctrl-C to kill the previous server instance (if it's still running) and restart it:

$ script/myapp_server.pl

Look for the three new model objects in the startup debug output:

...
 .-------------------------------------------------------------------+----------.
| Class                                                             | Type     |
+-------------------------------------------------------------------+----------+
| MyApp::Controller::Books                                          | instance |
| MyApp::Controller::Root                                           | instance |
| MyApp::Model::MyAppDB                                             | instance |
| MyApp::Model::MyAppDB::Author                                     | class    |
| MyApp::Model::MyAppDB::Book                                       | class    |
| MyApp::Model::MyAppDB::BookAuthor                                 | class    |
| MyApp::Model::MyAppDB::Role                                       | class    |
| MyApp::Model::MyAppDB::User                                       | class    |
| MyApp::Model::MyAppDB::UserRole                                   | class    |
| MyApp::View::TT                                                   | instance |
'-------------------------------------------------------------------+----------'
...

Again, notice that your "result source" classes have been "re-loaded" by Catalyst under MyApp::Model.

Include Authentication and Session Plugins

Edit lib/MyApp.pm and update it as follows (everything below StackTrace is new):

use Catalyst qw/
        -Debug
        ConfigLoader
        Static::Simple
        
        StackTrace
        
        Authentication
        Authentication::Store::DBIC
        Authentication::Credential::Password
        
        Session
        Session::Store::FastMmap
        Session::State::Cookie
        /;

The three Authentication plugins work together to support Authentication while the Session plugins are required to maintain state across multiple HTTP requests. Note that there are several options for Session::Store (Session::Store::FastMmap is generally a good choice if you are on Unix; try Cache::FileCache if you are on Win32) -- consult Session::Store and its subclasses for additional information.

Configure Authentication

Although __PACKAGE__->config(name => 'value'); is still supported, newer Catalyst applications tend to place all configuration information in myapp.yml and automatically load this information into MyApp->config using the ConfigLoader plugin. Here, we need to load several parameters that tell Catalyst::Plugin::Authentication where to locate information in your database. To do this, edit the myapp.yml YAML and update it to match:

---
name: MyApp
authentication:
    dbic:
        # Note this first definition would be the same as setting
        # __PACKAGE__->config->{authentication}->{dbic}->{user_class} = 'MyAppDB::User'
        # in lib/MyApp.pm (IOW, each hash key becomes a "name:" in the YAML file).
        #
        # This is the model object created by Catalyst::Model::DBIC from your
        # schema (you created 'MyAppDB::User' but as the Catalyst startup
        # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::User').
        # NOTE: Omit 'MyApp::Model' to avoid a component lookup issue in Catalyst 5.66
        user_class: MyAppDB::User
        # This is the name of the field in your 'users' table that contains the user's name
        user_field: username
        # This is the name of the field in your 'users' table that contains the password
        password_field: password
        # Other options can go here for hashed passwords

Inline comments in the code above explain how each field is being used.

TIP: Although YAML uses a very simple and easy-to-ready format, it does require the use of a consistent level of indenting. Be sure you line up everything on a given 'level' with the same number of indents. Also, be sure not to use tab characters (YAML does not support them because they are handled inconsistently across editors).

Use the Catalyst create script to create two stub controller files:

$ script/myapp_create.pl controller Login
$ script/myapp_create.pl controller Logout

NOTE: You could easily use a single controller here. For example, you could have a User controller with both login and logout actions. Remember, Catalyst is designed to be very flexible, and leaves such matters up to you, the designer and programmer.

Then open lib/MyApp/Controller/Login.pm, locate the sub index : Private method (this was automatically inserted by the helpers when we created the Login controller above), and delete this line:

$c->response->body('Matched MyApp::Controller::Login in Login.');

Then update it to match:

=head2 index

Login logic

=cut

sub index : Private {
    my ($self, $c) = @_;

    # Get the username and password from form
    my $username = $c->request->params->{username} || "";
    my $password = $c->request->params->{password} || "";

    # If the username and password values were found in form
    if ($username && $password) {
        # Attempt to log the user in
        if ($c->login($username, $password)) {
            # If successful, then let them use the application
            $c->response->redirect($c->uri_for('/books/list'));
            return;
        } else {
            # Set an error message
            $c->stash->{error_msg} = "Bad username or password.";
        }
    }

    # If either of above don't work out, send to the login page
    $c->stash->{template} = 'login.tt2';
}

This controller fetches the username and password values from the login form and attempts to perform a login. If successful, it redirects the user to the book list page. If the login fails, the user will stay at the login page but receive an error message. If the username and password values are not present in the form, the user will be taken to the empty login form.

Note that we could have used something like sub default :Private; however, the use of default actions is discouraged because it does not receive path args as with other actions. The recommended practice is to only use default in MyApp::Controller::Root.

Another option would be to use something like sub base :Path :Args(0) {...} (where the ... refers to the login code shown in sub index : Private above). We are using sub base :Path :Args(0) {...} here to specifically match the URL /login. Path actions (aka, "literal actions") create URI matches relative to the namespace of the controller where they are defined. Although Path supports arguments that allow relative and absolute paths to be defined, here we use an empty Path definition to match on just the name of the controller itself. The method name, base, is arbitrary. We make the match even more specific with the :Args(0) action modifier -- this forces the match on only /login, not /login/somethingelse.

Next, update the corresponding method in lib/MyApp/Controller/Logout.pm to match:

=head2 index

Logout logic

=cut

sub index : Private {
    my ($self, $c) = @_;

    # Clear the user's state
    $c->logout;

    # Send the user to the starting point
    $c->response->redirect($c->uri_for('/'));
}

As with the login controller, be sure to delete the $c-response->body('Matched MyApp::Controller::Logout in Logout.');> line of the sub index.

Create a login form by opening root/src/login.tt2 and inserting:

[% META title = 'Login' %]

<!-- Login form -->
<form method="post" action=" [% Catalyst.uri_for('/login') %] ">
  <table>
    <tr>
      <td>Username:</td>
      <td><input type="text" name="username" size="40" /></td>
    </tr>
    <tr>
      <td>Password:</td>
      <td><input type="password" name="password" size="40" /></td>
    </tr>
    <tr>
      <td colspan="2"><input type="submit" name="submit" value="Submit" /></td>
    </tr>
  </table>
</form>

Add Valid User Check

We need something that provides enforcement for the authentication mechanism -- a global mechanism that prevents users who have not passed authentication from reaching any pages except the login page. This is generally done via an auto action/method (prior to Catalyst v5.66, this sort of thing would go in MyApp.pm, but starting in v5.66, the preferred location is lib/MyApp/Controller/Root.pm).

Edit the existing lib/MyApp/Controller/Root.pm class file and insert the following method:

=head2 auto

Check if there is a user and, if not, forward to login page

=cut

# Note that 'auto' runs after 'begin' but before your actions and that
# 'auto' "chain" (all from application path to most specific class are run)
# See the 'Actions' section of 'Catalyst::Manual::Intro' for more info.
sub auto : Private {
    my ($self, $c) = @_;

    # Allow unauthenticated users to reach the login page.  This
    # allows anauthenticated users to reach any action in the Login
    # controller.  To lock it down to a single action, we could use:
    #   if ($c->action eq $c->controller('Login')->action_for('index'))
    # to only allow unauthenticated access to the C<index> action we
    # added above.
    if ($c->controller eq $c->controller('Login')) {
        return 1;
    }

    # If a user doesn't exist, force login
    if (!$c->user_exists) {
        # Dump a log message to the development server debug output
        $c->log->debug('***Root::auto User not found, forwarding to /login');
        # Redirect the user to the login page
        $c->response->redirect($c->uri_for('/login'));
        # Return 0 to cancel 'post-auto' processing and prevent use of application
        return 0;
    }

    # User found, so return 1 to continue with processing after this 'auto'
    return 1;
}

Note: Catalyst provides a number of different types of actions, such as Local, Regex, and Private. You should refer to Catalyst::Manual::Intro for a more detailed explanation, but the following bullet points provide a quick introduction:

The majority of application use Local actions for items that respond to user requests and Private actions for those that do not directly respond to user input.
There are five types of Private actions: begin, end, default, index, and auto.
With begin, end, default, index private actions, only the most specific action of each type will be called. For example, if you define a begin action in your controller it will override a begin action in your application/root controller -- only the action in your controller will be called.
Unlike the other actions where only a single method is called for each request, every auto action along the chain of namespaces will be called. Each auto action will be called from the application/root controller down through the most specific class.

By placing the authentication enforcement code inside the auto method of lib/MyApp/Controller/Root.pm (or lib/MyApp.pm), it will be called for every request that is received by the entire application.

Displaying Content Only to Authenticated Users

Let's say you want to provide some information on the login page that changes depending on whether the user has authenticated yet. To do this, open root/src/login.tt2 in your editor and add the following lines to the bottom of the file:

<p>
[%
   # This code illustrates how certain parts of the TT 
   # template will only be shown to users who have logged in
%]
[% IF Catalyst.user_exists %]
    Please Note: You are already logged in as '[% Catalyst.user.username %]'.
    You can <a href="[% Catalyst.uri_for('/logout') %]">logout</a> here.
[% ELSE %]
    You need to log in to use this application.
[% END %]
[%#
   Note that this whole block is a comment because the "#" appears
   immediate after the "[%" (with no spaces in between).  Although it 
   can be a handy way to temporarily "comment out" a whole block of 
   TT code, it's probably a little too subtle for use in "normal" 
   comments.
%]

Although most of the code is comments, the middle few lines provide a "you are already logged in" reminder if the user returns to the login page after they have already authenticated. For users who have not yet authenticated, a "You need to log in..." message is displayed (note the use of an IF-THEN-ELSE construct in TT).

Try Out Authentication

Press Ctrl-C to kill the previous server instance (if it's still running) and restart it:

$ script/myapp_server.pl

IMPORTANT NOTE: If you happen to be using Internet Explorer, you may need to use the command script/myapp_server.pl -k to enable the keepalive feature in the development server. Otherwise, the HTTP redirect on successful login may not work correctly with IE (it seems to work without -k if you are running the web browser and development server on the same machine). If you are using browser a browser other than IE, it should work either way. If you want to make keepalive the default, you can edit script/myapp_server.pl and change the initialization value for $keepalive to 1. (You will need to do this every time you create a new Catalyst application or rebuild the myapp_server.pl script.)

Now trying going to http://localhost:3000/books/list and you should be redirected to the login page, hitting Shift+Reload if necessary (the "You are already logged in" message should not appear -- if it does, click the logout button and try again). Note the ***Root::auto User not found... debug message in the development server output. Enter username test01 and password mypass, and you should be taken to the Book List page.

Open root/src/books/list.tt2 and add the following lines to the bottom:

<p>
  <a href="[% Catalyst.uri_for('/login') %]">Login</a>
  <a href="[% Catalyst.uri_for('form_create') %]">Create</a>
</p>

Reload your browser and you should now see a "Login" and "Create" links at the bottom of the page (as mentioned earlier, you can update template files without reloading the development server). Click the first link to return to the login page. This time you should see the "You are already logged in" message.

Finally, click the You can logout here link on the /login page. You should stay at the login page, but the message should change to "You need to log in to use this application."

USING PASSWORD HASHES

In this section we increase the security of our system by converting from cleartext passwords to SHA-1 password hashes.

Note: This section is optional. You can skip it and the rest of the tutorial will function normally.

Note that even with the techniques shown in this section, the browser still transmits the passwords in cleartext to your application. We are just avoiding the storage of cleartext passwords in the database by using a SHA-1 hash. If you are concerned about cleartext passwords between the browser and your application, consider using SSL/TLS, made easy with the Catalyst plugin Catalyst::Plugin:RequireSSL.

Get a SHA-1 Hash for the Password

Catalyst uses the Digest module to support a variety of hashing algorithms. Here we will use SHA-1 (SHA = Secure Hash Algorithm). First, we should compute the SHA-1 hash for the "mypass" password we are using. The following command-line Perl script provides a "quick and dirty" way to do this:

$ perl -MDigest::SHA -e 'print Digest::SHA::sha1_hex("mypass"), "\n"'
e727d1464ae12436e899a726da5b2f11d8381b26
$

Note: You should probably modify this code for production use to not read the password from the command line. By having the script prompt for the cleartext password, it avoids having the password linger in forms such as your .bash_history files (assuming you are using BASH as your shell). An example of such a script can be found in Appendix 3.

Switch to SHA-1 Password Hashes in the Database

Next, we need to change the password column of our users table to store this hash value vs. the existing cleartext password. Open myapp03.sql in your editor and enter:

--
-- Convert passwords to SHA-1 hashes
--
UPDATE users SET password = 'e727d1464ae12436e899a726da5b2f11d8381b26' WHERE id = 1;
UPDATE users SET password = 'e727d1464ae12436e899a726da5b2f11d8381b26' WHERE id = 2;
UPDATE users SET password = 'e727d1464ae12436e899a726da5b2f11d8381b26' WHERE id = 3;

Then use the following command to update the SQLite database:

$ sqlite3 myapp.db < myapp03.sql

Note: We are using SHA-1 hashes here, but many other hashing algorithms are supported. See Digest for more information.

Enable SHA-1 Hash Passwords in `Catalyst::Plugin::Authentication::Store::DBIC`

Edit myapp.yml and update it to match (the password_type and password_hash_type are new, everything else is the same):

---
name: MyApp
authentication:
    dbic:
        # Note this first definition would be the same as setting
        # __PACKAGE__->config->{authentication}->{dbic}->{user_class} = 'MyAppDB::User'
        # in lib/MyApp.pm (IOW, each hash key becomes a "name:" in the YAML file).
        #
        # This is the model object created by Catalyst::Model::DBIC from your
        # schema (you created 'MyAppDB::User' but as the Catalyst startup
        # debug messages show, it was loaded as 'MyApp::Model::MyAppDB::User').
        # NOTE: Omit 'MyApp::Model' here just as you would when using 
        # '$c->model("MyAppDB::User)'
        user_class: MyAppDB::User
        # This is the name of the field in your 'users' table that contains the user's name
        user_field: username
        # This is the name of the field in your 'users' table that contains the password
        password_field: password
        # Other options can go here for hashed passwords
        # Enabled hashed passwords
        password_type: hashed
        # Use the SHA-1 hashing algorithm
        password_hash_type: SHA-1

Try Out the Hashed Passwords

Press Ctrl-C to kill the previous server instance (if it's still running) and restart it:

$ script/myapp_server.pl

You should now be able to go to http://localhost:3000/books/list and login as before. When done, click the "Logout" link on the login page (or point your browser at http://localhost:3000/logout).

Note: If you receive the debug screen in your browser with a Can't call method "stash" on an undefined value... error message, make sure that you are using v0.07 of Catalyst::Plugin::Authorization::ACL. The following command can be a useful way to quickly dump the version number of this module on your system:

perl -MCatalyst::Plugin::Authorization::ACL -e 'print $Catalyst::Plugin::Authorization::ACL::VERSION, "\n";'

USING THE SESSION FOR FLASH

As discussed in Part 3 of the tutorial, flash allows you to set variables in a way that is very similar to stash, but it will remain set across multiple requests. Once the value is read, it is cleared (unless reset). Although flash has nothing to do with authentication, it does leverage the same session plugins. Now that those plugins are enabled, let's go back and improve the "delete and redirect with query parameters" code seen at the end of the Basic CRUD part of the tutorial.

First, open lib/MyApp/Controller/Books.pm and modify sub delete to match the following:

=head2 delete 

Delete a book
    
=cut

sub delete : Local {
    # $id = primary key of book to delete
    my ($self, $c, $id) = @_;

    # Search for the book and then delete it
    $c->model('MyAppDB::Book')->search({id => $id})->delete_all;

    # Use 'flash' to save information across requests until it's read
    $c->flash->{status_msg} = "Book deleted";
        
    # Redirect the user back to the list page with status msg as an arg
    $c->response->redirect($c->uri_for('/books/list'));
}

Next, open root/lib/site/layout and update the TT code to pull from flash vs. the status_msg query parameter:

<div id="header">[% PROCESS site/header %]</div>

<div id="content">
<span class="message">[% status_msg || Catalyst.flash.status_msg %]</span>
<span class="error">[% error_msg %]</span>
[% content %]
</div>

<div id="footer">[% PROCESS site/footer %]</div>

Try Out Flash

Restart the development server and point your browser to http://localhost:3000/books/url_create/Test/1/4 to create an extra book. Click the "Return to list" link and delete the "Test" book you just added. The flash mechanism should retain our "Book deleted" status message across the redirect.

NOTE: While flash will save information across multiple requests, it does get cleared the first time it is read. In general, this is exactly what you want -- the flash message will get displayed on the next screen where it's appropriate, but it won't "keep showing up" after that first time (unless you reset it). Please refer to Catalyst::Plugin::Session for additional information.

AUTHOR

Kennedy Clark, hkclark@gmail.com

Please report any errors, issues or suggestions to the author. The most recent version of the Catalyst Tutorial can be found at http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Runtime/lib/Catalyst/Manual/Tutorial/.

To install Task::Catalyst::Tutorial, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Task::Catalyst::Tutorial

CPAN shell

perl -MCPAN -e shell
install Task::Catalyst::Tutorial

For more information on module installation, please visit the detailed CPAN module installation guide.

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